I'm not a doctor so act on his or her recommendation. I found a Cleveland Clinic citation that might put your mind at ease as concerns the reported 4 mm nodules - here: https://my.clevelandclinic.org/health/diseases_conditions/hic_Pulmonary_Nodules. Note the concern starts at 4 cm and yours are much smaller than the concern level.
I am a lung cancer survivor and my scan reports are full of nodule observations. The major challenge for my radiologist and oncologist is correlating previous scans to current results. Complexity is introduced because sometimes the nodules grow and or recede scan-to-scan. All of them for the last 8 years have not been cancer!
There is no playbook. Stage IV SCLC with extended metastasis is nasty.
My father was so broken inside while I was in treatment, he couldn't talk to me. I didn't understand then; I do now but he passed before my disease was arrested and we can't talk about it. If I could, I guess I'd tell him there is a time to live and a time to grieve and he got the order reversed. But, I understand why. It's that feeling of hopelessness you are describing compounded by your belief that you can't help your family member. But you can. How?
Focus on the little things. While in treatment and uncertain about outcomes, my wife became a master of the little things. She'd tell me in the morning, we were going to have breakfast for dinner at Denny's. She'd describe all the Grand Slam possibilities and before I realized it, I was looking forward to something - to something I would enjoy. Then, she'd bring me a bag of Gummy Bears and I inhale Gummys but she'd dole them out to me one at a time, making me keep one in my mouth till it nearly melted away. Then she'd engage me in choosing the best flavor. Then she'd argue with my choice. Then, I'd forget about my cancer. Just for a while but those thousands of little things my wife dreamed up strung together a long period of enjoyment.
It is not how much time we have left; it is what we do with the time we have. Help your family member find joy in the little things he or she loves about life. Be a master of the little things.